lol no man a 540 size lathe motor for a com lathe or rc tire truer lathe,there just really high turn motors that produce lots of torque to swing props without the use of reductions.trust me a direct drive 45 turn lathe will be plenty horsepower and rpm for up to a 2" wheel
these motors
http://www3.towerhobbies.com/cgi-bin...SM&C=CKA&V=INT
www.cornwallmodels.com has plenty cheap props and shafts and fast shipping
a boat that size single screw would need a 1.5- 1 3/4" prop,or a 4 blade 40-45mm